The simple MRP journal in Microsoft Dynamics 365 Business Central is a planning tool that only creates new order suggestions. Unlike the standard MRP planning worksheet, also called the requisition worksheet, it does not reschedule, cancel, or adjust existing orders. It only suggests new supplies.
The simple MRP runs around 20 times faster than the standard MRP. You control its behaviour through templates, and you can build an unlimited number of templates with different logic for different purposes and different times of year.
You can set templates to trigger on ending inventory below zero, on safety stock, or on reorder point. You can calculate per location, combine locations, or combine variants. You can break down the full BOM hierarchy by running for all low-level codes, handling both MPS and MRP in one calculation.
What the simple MRP journal does and how it differs from standard MRP
The simple MRP journal only creates new order suggestions. The true MRP journals, the planning worksheet or requisition worksheet, give you full flexibility to reschedule and adjust existing supply. The simple MRP deliberately leaves that out and focuses only on suggesting new supplies.
It sits between two extremes. It has more logic and flexibility than dynamic replenishment, where you do all the planning manually. But it is simpler than the full MRP planning journals. The main advantage is speed: the simple MRP runs around 20 times faster than the standard MRP, because it has fewer scenarios to handle.
Running a template to find critical items
The functionality ships with a set of templates, each containing different logic. The most basic one is “Find critical items”. When you run it, it finds all items with an ending inventory below zero on the location you have selected, and suggests filling up to zero. The suggested quantity to order is calculated from the template setup, so for one item you might get a suggestion of five and for another a suggestion of three.
This is a simple calculation, but the result is a clear list of the items that are critical right now.
How the template card controls the calculation
All the complexity sits in the template card. Once you understand the fields on both the template card and the related supply template, you can build exactly the logic you need.
The template card defines two main things. First, where you want to calculate from. Second, which demands and supplies to include. In the basic example, the template triggers on ending inventory level zero rather than on safety stock or reorder point.
Triggering on ending inventory means you do not care if the item dips below zero within a period, because that is only a matter of moving dates around, and there are other tools for that. When the ending inventory is positive, you usually do not want the item flagged as critical.
The template card also gives you control through several check marks. You can calculate per location, calculate with locations combined, or combine variants. There is a lot of functionality available, and the standard templates cover common scenarios out of the box. You can also build your own templates with practically unlimited logic.
Running for all low-level codes to break down the hierarchy
One of the more advanced options is “Run for all low-level codes”. With this enabled, the calculation runs one location code at a time, breaks down the BOM hierarchy, automatically suggests quantity to order, and automatically carries out the result.
Take the template “Find critical items, all levels”. It still triggers on zero ending inventory, so it still finds critical items. The difference is the check mark in “Run for all low-level codes”. It suggests quantity to order based on a supply template you set up, which in this case looks from ending inventory up to zero, applies order modifiers, and rounds up.
With this template, the calculation starts at low-level code zero. It suggests the quantity to order, sets the action message, and transfers the lines into the planning worksheet. Then it moves to low-level code one, including the dependent demand generated from the level above, and continues down through the hierarchy.
The result handles both MPS and MRP at the same time, breaking down the full hierarchy while still only suggesting new orders. This produces more lines, so it takes longer to run, but it is still far faster than the standard MRP.
From calculation to planning worksheet
When you set a template to set the action message and carry out, it places the check mark on each line and transfers the lines into the planning worksheet. If you carry out a calculation for critical items, the truly critical items, the ones at the top level like an MPS, land in the planning worksheet ready for you to act on.
When you run the all-levels template instead, the planning worksheet fills with the full breakdown. The simple MRP journal itself ends up empty, because the lines have all been transferred. Scroll through the planning worksheet and you find many more lines, covering the complete breakdown of items down through every level.
Building a library of templates for different needs
The two templates above are only examples. You can set up templates to calculate below reorder point or safety stock, to create purchase and transfer lines, to run several templates in iteration after each other, to break down forecast, and much more. There is no real limit to what you can configure.
A good planner might keep hundreds of templates available, each set up for a different time of year and a different purpose. That is the intended way to work with the simple MRP.
Q&A
What is the difference between the simple MRP journal and the standard MRP planning worksheet?
The simple MRP journal only creates new order suggestions. The standard MRP planning worksheet, or requisition worksheet, also reschedules and adjusts existing supply. The simple MRP focuses only on suggesting new supplies, which makes it around 20 times faster than the standard MRP.
How fast is the simple MRP compared to standard MRP?
The simple MRP runs around 20 times faster than the standard MRP, because it only suggests new orders and handles fewer scenarios.
Can the simple MRP break down the full BOM hierarchy?
Yes. With the “Run for all low-level codes” option, the calculation starts at level zero, transfers suggestions into the planning worksheet, then moves down through each low-level code including the dependent demand. This handles both MPS and MRP in one calculation while still only suggesting new orders.
What can a template trigger on?
A template can trigger on ending inventory below zero, on safety stock, or on reorder point. You define this on the template card along with which demands and supplies to include.
Why does triggering on ending inventory ignore dips below zero within a period?
When you trigger on ending inventory, a temporary dip below zero within the period does not flag the item as critical, because that is only a matter of moving dates around. There are other tools for rescheduling. If the ending inventory is positive, you usually do not want the item flagged as critical.
How many templates can I create?
There is no practical limit. You can build templates for calculating below reorder point or safety stock, creating purchase and transfer lines, running several templates in iteration, breaking down forecast, and more. A planner might keep hundreds of templates for different times of year and different purposes.